Telephone system



June 1930- E. P. G. WRIGHT 2, 51

TELEPHONE SYSTEM Filed Oct. 26. 192B OPERATED a/v 190mm 5TP T ONElNVENTOH sM0/v0 E 61 WRIGHT A fro/ms? Patented June 10, 1930 UNITEDSTATES PATENT OFFICE ESMOND P. G. WRIGHT, OI" BURWOOD, ENGLAND, ASSIGNORTO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., ACORPORATION OF NEW YORK TELEPHONE SYSTEM Application filed October 26,1928, Serial No. 315,141, and in Great Britain December 17, 1927.

This invention relates in general to telephone systems and moreparticularly to systems which employ automatic switches for establishingconversational connections.

The object of this invention is to increase the capacity of selectiveswitches and the flexibility of the system in which these switches areincorporated.

Heretofore selecting switches with two sets of brushes and two terminalbanks have been arranged so that both sets of brushes are operativelyassociated with their corresponding banks during the automatic selectionof an idle set of terminals and arranged so that, after said selection,the set of brushes, which is in contact with the selected set ofterminals, is rendered effective to the exclusion of the other set ofbrushes. Other selecting switches have been so arranged that only oneset of brushes is operatively associated with its corresponding bankduring the automatic selection of an idle set of terminals, brushselection having preceded said terminal selection. In some of theseswitches brush selection depends upon the character of the digit whichcontrols the primary movement of the switch and in others it dependsupon the character of a digit which is prefixed to the di it whichcontrols the primary movement 0 the switch. A third class of selectingswitches has been arranged to absorb the first series of pulses whichare received, such switches being used in areas in which the subscribersnumbers are made up of a varying number of digits' According to thisinvention a switch is provided having a plurality of sets of brushescooperating with respective banks of terminals and so arranged thatunder certain conditions all sets of brushes are efi'ectii'e tosimultaneously test the terminals in their banks and under otherconditions one set of brushes is effective to the exclusion of the othersets.

According to another feature of the invention a switch is provided witha plurality of sets of brushes which cooperate with respective banks ofterminals, and with a set of contact springs operable in certain primarypositions of the switch for restoring the brushes to normal and forcausing one only of the sets of brushes to be operatively associatedwith its terminal bank during the automatic selection, of an idle set ofterminals, which follows a repositioning of the brushes by a primarymovement of the switch.

To illustrate how the new switch may be used, assume an exchange area inwhich numbers from 2,000 to 7,999, from 80,000 to 81,999 and from 88,000to 89,999 are assigned to subscribers lines, the number 92 is assignedfor calls, to complaint operator, and 0 is assigned for calls to tollrecording operator. A first selector in an exchange of such an area,arranged .in accordance with this invention, provides groups of 20trunks each when the first digit of the called numher is one of the sixdigits 2, 3, 4, 5, 6 and 7, both sets of brushes being operativelyassociated with the contacts in their respective banks, so as toautomatically select the first idle outlet encountered by either set ofbrushes. When the first digit of the called number is 0 or 9, groups often trunks each are provided and the set of brushes which cooperateswith the main bank is rendered effective to the exclusion of the otherset of brushes. When the first digit of the called number is 8 thebrushes are restored to normal after having been stepped to the 8thlevel; the next digit of the called number being either 0, 1, 8 or 9 theset of brushes which cooperates with the auxiliary bank is renderedeifective to the exclusion of the set of brushes which cooperates withthe main bank. Thus groups of 20 outlets each are provided on thesecond, third, fourth, fifth, sixth and seventh levels, and twoindependent groups of 10 outlets each are provided on each of theremaining levels.

Referring to the drawing which diagrammatically illustrates oneembodiment of the invention, A represents a calling subscriberssubstation which is automatically connected either by a line switch asindicated schematically, or by a line finder, with an idle selector S.The selector is of the step-by-step type and has a capacity of 200 setsof terminals divided into two banks hereinafter referred to as the mainand auxiliary banks. There are 100 sets of terminals per bank dividedinto 10 levels, 10 sets of terminals per level. The selector is equippedwith two sets of brushes arranged on a single shaft so that brushes 19,2t) and 21 cooperate with the main bank and brushes 22, 23 and 24:cooperate with the auxiliary bank. By a vertical movement of the shattthe brushes are stepped up to the desired level and by a rotary movementthey are advanced to make contact suc essively with the sets ofterminals in the selected level. The contact springs of switching deviceX are operated when the brushes are stepped to a certain level which inour illustrati n we have as sumed to be level 8. The contact springs ofswitching device Y are operated on certain other levels which in ourillustration we have assume-d to be levels 2, 8, 4, 5. 6 and 7. Relay 9switches the incoming circuit from one set of brushes to the other andrelay 1O cooperates with contact springs X to cause the restoration ofthe brushes to normal. Except for these modifications the selector oneot' the usual and well-known construction.

Upon seizure of the selector, relay 1 operates in a circuit from batterythrough its upper winding, through the top outer contact of relay 7,line 11, bottom outer contact of relay 7, lower winding of relay 1,contact 17 ot the eleventh rotary step springs, and secondary winding ofthe dial tone induction coil, to ground. Relay 1 eperates relay 2 in acircuit. from battery through its winding, to ground on the top innerarmature of relay 7. Relay 2 connects ground to conductor 12 for thepurpo-=e oi holding the antecedent switches.

When the subscribers calling device is operated to send a series ofpulses corresponding to the first digit of the callezL number, relay 1releases and reoperates each time the line circuit is opened and closedby the calling device. Relay 2 is slow to release and its contactsremain in the operated position during pulsing although the circuitthrough its winding is opened every time relay 1 relcasts. Each releaseof relay 1 closes a circuit from ground on the top inner armature ofrelay '7. through the back contact of relay 1. front contact of relay 2,Winding of relay and winding of vertical stepping magnet to battery,operating relay 3 and magnet The operation of magnet 4 steps the brushesup to the first level thereby closing oil-normal springs ON. lVith relay3 operated and the ON springs closed relay 5 operates in a circuit frombattery through its windings, through contact 18 of the eleventh rotarystep springs, contact 1st of the ON springs, contact 16 of the Xsprings,

and front contacts of relays 3 and 2. to ground. Relay 5 locks, undercontrol of the rotary stepping magnet G, to ground on the top innerarmature of relay'T. Each rcoperation of relay 1 opens the circuitthrough the windings of relay 3 and magnet 4, so that vertical magnet 4operates and releases as many times as there are units in the firstdigit dialled, stepping the brushes up to the corresponding level. Relay3 is slow to release and holds operated until all of the pulsescorresponding to the first digit have been received.

The further operation of the switch depends upon the level to which thebrushes are stepped by the first set of pulses received. Assume that thefirst digit of the called number is either 0 or 9 and that the brusheshave been stepped to the corresponding level. Since neither the X nor Ycontact springs are operated on either of these levels, neither ofrelays 9 or 10 is operated. The release of relay 3 closes a circuit frombattery through the winding of rotary stepping magnet 6 through the backcontact of relay 3 and front contact of relay 2, to ground. Theoperation of magnet 6 in this circuitrotates both sets of brushes intocontact with the first set of terminals in the selected l vels of theirrespective banks, but, since relay 9 is not operated, brushes 19, and 21are effective to the exclusion of brushes 22, and 24. Relay 5 releaseswhen magnet 6 operates, thus causing the release of magnet 6. \Vithmagnet 6 released, a circuit is closed from battery through the windingsof relay 5, through contact 18 of the eleventh rotary step springs,contact ll of the ON springs, contact 16 of the X springs, back contactof the rotarv magnet (5, Winding of relay '7. and from contact of relay2, to ground. If the first set of terminals in the main bank is idlerelay 7 operates, but relay 5 is marginal and does not operate in thiscircuit. If this set of terminals is busy, relay 5 reoperates and relay7 does not operate since its winding is short-circuited by ground on theterminal with which test brush 21 in contact. The reoperation of relay 5causes the reoperation of rotary stepping magnet (3, advancing thebrushes to the next set of terminals. The brushes are in this mannersuccessively advanced from one set of terminals to the next until anidle set is encountered, whereupon relay 7 operates to prevent theirfurther advance. Relay switches the incoming circuit from the windingsof relay 1 to brushes 19 and 20, which are in contact with the terminalsor" the selected trunk, thereby causing the release of relays l and 2.By the operation of relay 7 ground is temporarily connected through thefront contact of relay 2, bottom inner front contact of relav 7,

- 1 relay 9.

back contact of relay 9, and through test brush 21 to the test terminalof the selected I operation of release magnet 8 in a circuit frombattery through its winding, through off-normal contact 13, back contactof relay 2. back contact of relay 1, and back contact of relay 7, toground. The operation of the release magnet causes the switch to berestored to normal.

N ow assume that the first digit of the called number is one of thedigits 2, 3, 4, 5, 6 and 7. After the brushes have been stepped to oneof these levels, springs Y are operated thereby causing the operation ofAfter the first series of pulses have been received the release of relay3 causes the operation of the rotary stepping magnet 6 and theconsequent rotation of both sets of brushes into contact with the firstset of terminals in the selected level of their respective banks. Theoperation of magnet 6 releases relay and the release of relay 5 releasesmagnet 6. If the terminals, with which brushes 19, 20 and 21 are incontact, are idle, the release of relay 5 causes the release of relay 9.With relay 9 and magnet 6 released, a circuit is closedfrom batterythrough the windings of relay 5,, through contact 18 of the eleventhrotary step springs, contact 14 of the ON springs, contact 16 of springsX, back contact of magnet 6, winding of relay 7, and front contact ofrelay 2, to ground. Relay 7 operates but relay 5 does not operate inthis circuit. The release of relay 9 and operation of relay 7 connectsthe incoming circuit to brushes 19 and 20, and connects ground throughthe top inner contact of relay 2,

front contact of relay 7 and back contact of relay 9, to brush 21, thusrendering this set of terminals busy to any other hunting selector. Ifthe terminals, with which brushes 19, 20 and 21 are in contact, arebusy, relay 9 holds in a circuit from battery through its winding,through the back contact of relay 10, front contact of relay 9, backcontact of relay 7, front contact of relay 2, and test brush 21 toground on the test terminal; and if at the same time the terminals, withwhich brushes 22, 23 and 24 are in contact, are idle, relay 7 operatesas soc-n as magnet 6 releases.

Relay 7 connects a temporary busy ground through test brush 24 to thetest terminal of the selected set, and connects the incoming circuitthrough front contacts of relay 9 and through brushes 22 and 23 to theterminals of the selected idle trunk. If both sets of brushes are incontact with busy sets of terminals relay 9 holds, when relay 5releases; but relay 7 does not operate, since its winding isshort-circuited by the busy ground on the test terminal with which brush24 is in contact. lVhen magnet (3 releases, relay 5 reoperates closingthe circuit through the winding of rotary magnet (3. Thus, magnet 6 isreoperated after each rotary step, if both sets of brushes are incontact with busy sets of terminals; and the brushes are advancedsuccessively from one set of terminals to the next until an idle set ofterminals is encountered, at which time relay 7 operates. If relay 9 hasreleased the operation of relay 7 connects the incoming circuit tobrushes 19 and 20 but if relay 9 has not released the operation of relay7 connects the incoming circuit to brushes 22 and 23. The furtheroperation of the switch is similar to that described when the firstdigit of the called number is either 0 or 9.

Consider next the operation of the selector if the first digit of thecalled number 8. With the brushes stepped up to the eighth level,springs X are operated, thereby releasing relay 5. pulses have beenreceived the release of relay 3 closes a circuit from battery throughthe upper winding of relay 10, through con tact 15 of springs X, backcontact of relay 10, back contact of relay 3, and front contact of relay2, to ground. Relay is a two-step relay and when energized in thiscircuit closes its bottom inner armature and front contact Withoutclosing or opening any other contacts, and when thus operated its lowerwinding is short-circuited by contact of springs X. The release of relay3 also closes a circuit from battery through the winding of releasemagnet 8, through the back contact of relay 10, contact 15 of springs X,back contact of relay 10, back contact of relay 3, and front contact ofrelay 2, to ground. Release magnet 8 operates in this circuit thusrestoring the brushes to normal. The opening of contact 15 removes theshort-circuit from the lower winding of relaylO, and this relay nowcompletely up crates. When fully operated relay 10 locks in a circuitfrom battery through its upper and lower windings in series, through itsown front contact and front contact of relay 2, to ground. The completeoperation of relay 10 also closes an obvious circuit through the windingof relay 9, and the resulting operation of relay 9 renders brushes 22,23 and 241 effective, to the exclusion of brushes 19, and 21. The nextseries of pulses received by the selector steps the brushes up to one oflevels 0, 1, 8 and 9 according to which of these corresponds to theAfter the first series of second digit of the called number. lVhen theswitch is moved elf-normal by the first pulse of this second series,relay 5 reoperates in a circuit from battery through its windings,through contact 18 of the eleventh rotary step springs, contact 14 ofthe ON springs, front contact of relay 10, front contact of relay 3, andfront contactof relay 2, to ground. The release of relay 3 attcr thelast pulse has been received closes the circuit through the rotarystepping magnet- 6, both sets of brushes being advanced into contactwith the first set of terminals in their respective banks. It the firstset of terminals in the auxiliary bank is idle, relay 7 operates as soonas magnet (3 releases. It the first set of terminals is busy relay 5reoperates in a circuit from battery through its winding, throughcontact 18 of the eleventh rotary step springs, contact l i of the OKsprings, frontcontact of relay 10, back contact 01? magnet (5. backcontact of relay 7, front contact of relay 9, and test brush 2%, toground on the test terminal of the busy set, and r lay 7 does notoperate since the ground on the test terminal. shortcircuits itswinding. The rcoperation of relay 5 closes the circuit t'or rotarystepping magnet 6 thereby advancing the brushes to the next set ofterminals. \Vhen an idle s of terminals is encountered the operation ofrelay 7 connects the incoming c 'cuit through t'ront contacts of relay 9and through brushes 22 and 23 to the terminals of the selected trunk.The further operation of the switcn is similar to that described whenthe irst digit of the called number is either 0 or 9.

From the foregoing explanation it will be seen that the presentinvention provides in a simple method a switch capable of performing thecombined functions of a selector havin access to 20 trunks per group, aselector having access to 1.0 trunks per group. and a selector capableof absorbing the first digit dialled. It will be further noted that thesame test relay serves to test in the main bank and in the auxiliarybank. It is understood that a similar arrangement may be applied to aPBX final selector.

\Vhat is claimed is:

l. The combination in an automatic switch of a pluralit of terminalbanks, a plurality or sets of brushes for cooperating with said terminalbanks, means for operatively associating any one 01" said sets ofbrushes pith the terminals in its corresponding bank, and means foroperatively associating all of said sets simultaneously with theircorresponding banks.

2. In an automatic switch, a main terminal bank and an auxiliaryterminal bank, a set of brushes for cooperating with the main bank, aset of brushes for cooperating with the auxiliary bank. means effectivein certain primary positions of the switch for operatively associatingall of said sets oil brushes with their corresponding banks, meanseffective in other primary positions of the switch for causing therestoration oi": the brushes to normal, and means ell'ective afteranother primary movement of the switch for operatively associating oneof said sets of brushes with its corresponding bank to the exclusion ofthe other set.

3. In an automatic switch, a main terminal bank and an auxiliaryterminal l: nk. each comprising a plurality of levels of terminals,groups of trunks connected to the terminals in certain levels of themain bank, independent groups of trunks connected to the terminal in thesame levels of the auxiliary bank, and independent groups of trunksconnected to the terminals in other loves of both banks.

4. In an automatic switch, a first terminal bank, a second terminalbank, a set of brushes for cooperating with said first bank, a set ofbrushes for cooperati with said second bank, means "for operativelyassociating either of said sets of brushes with the terminals in itscorrcspoml bank, and means for operatively a both of said sets ofbrushes with the terminals of both banks simultaneously.

In a two-motion selectingswitch, a main terminal bank and an auxiliaryterminal. bank, a set of brushes for cooperating with the main bank, aset of brushes for (o operating with the auxiliary bank, and meanseffective in certain primary positions of the switch for determiningwhether the brushes in their further movement shall have access to themain bank, or to the auxiliary bank, or to both of said bankssimultaneously.

6. In a two-motion selecting switch. dupli- "ate sets of brushes andterminal banks. a test relay, a contact device effective in certainprimary positions of the switch, and means controlled by said test relayand said contact device for switching from one set of brushes to theother.

7. The combination in a two-motion select ing switch of duplicate setsof brushes and terminal banks, means for switching from one set ofbrushes to the other, means tor testing contacts in both bankssimultaneously, and means actuated in a certain primary position of theswitch for restoring the brushes to normal and for operating said brushswitching means.

8. The combination. of a calling sul scribers substation, a callingdevice at said station, a two-motion selecting switch comprisingduplicate sets of brushes and termi nal banks, means for connecting saidstation with said switch, means for positioning both sets of brushes bya primary movement of the switch, said means actuated by impluses ofcurrent created by operation of the til) Elf)

aforementioned calling device, and means actuated in certain primarypositions of the switch for restoring the brushes to normal to effect anabsorption of the first series of current impulses.

9. In an automatic switch, a first terminal bank and a second terminalbank, a set of brushes for cooperating with said first bank, a set ofbrushes for cooperating with said second bank, a relay for switchingfrom one set of brushes to the other, a contact device actuated incertain primary positions of the switch for operating said switchingrelay, a second contact device actuated in some other primary positionof the switch for restoring the brushes to normal, and means effectiveafter said restoring of the brushes and after another primary movementof the switch for rendering the second set of brushes effective to theexclusion of the first set.

10. In a two-motion selecting switch, afirst terminal bank and a secondterminal bank, a set of brushes for cooperating with said first bank, aset of brushes for cooperatin with said second bank, a relay forswitching from the first set of brushes to the second set, a contactdevice actuated in certain primary positions of the switch for operatingsaid switching relay, a second relay, a second contact device actuatedin some other primary position of the switch for operating said relayand restoring the brushes to normal, a test relay efl'ective to test theterminals in the first bank when said switching relay is not operatedand effective to test the terminals in the second bank when saidswitching relay is operated, and means comprising said second contactdevice and said second relay effective after said restoring of thebrushes to normal and after another primary movement of the switch forrendering said second set of brushes effective to the exclusion of thefirst set.

11. In a two-motion automatic switch, a first terminal bank and a secondterminal bank, a set of brushes for cooperating with said first bank, aset of brushes for cooperating with said second bank, a relay forswitching from the first'set of brushes to the second set, a test relayefli'ective to test the terminals in the first bank when said switchingrelay is not operated and effective to test the terminals in the secondbank when said switching relay is operated, a contact device actuated incertain rimary positions of the switch for operating said switchingrelay, means including said switching relay and said test relayeffective when said contact device is operated for testing the terminalsin both banks simultaneously, a third relay, a second contact deviceactuated in some other primar position of the switch for operating saithird relay and for restoring the brushes to normal, and means includingsaid test relay and said third relay effective after said restoring ofthe brushes to normal and after another primary movement of the switchfor testing the terminals in the second bank to the exclusion of theterminals in the first'bank.

12. In a two-motion automatic switch, a first terminal bank and a secondterminal bank, a set of brushes for cooperating with said first bank, aset of brushes for cooperating with said second bank, a relay forswitching from the first set of brushes to the second set, a test relay,a contact device actuated in certain primary positions of the switch foroperating said switching relay, a third relay, a second contact deviceactuated in some other primary position of the switch for operating saidthird relay and for rcstoring the brushes to normal, means includingsaid test relay effective when said switching relay and said third relayare not operated for testing the terminals in the first bank to theexclusion of the terminals in the second bank, means includin said testrelay and said switching relay elIective when the first mentioned ofsaid contact devices is actuated for testing the terminals in both bankssimultaneously, and means including said test relay and said switchingrelay effective after said restoring of the brushes to normal and afteranother primary movement of the switch for testing the terminals in thesecond bank to the exclusion of the terminals in the first bank.

In witness whereof, I hereunto subscribe my name this first day ofOctober, 1928.

ESMOND P. G. WVRIGHT.

